Harvard Business School published some tips regarding essays and recommendations on their admissions blog:


Let me share some approaches that are NOT particularly helpful to your application:

  • Essays that are basically a paragraph version of your resume: This is surprisingly common: I went to college X then decided to take job Y and that led me to job Z, and now I’m applying to HBS. There’s nothing “wrong” with this essay per se; it just doesn’t add much to your application because we already know all of that from the other elements of your application. Of course you can build on things that are raised in other parts of the application—just make sure it’s additive.
  • Essays that are too long: I wish I could give you a general rule that essays over X words are too long, but sometimes you need more space to bring things together. And that’s the reason there’s no word limit. Use your best judgment, and try to be clear and concise in your writing. What do we need to know to understand you that hasn’t been addressed elsewhere? (And what don’t we need to know?)
  • Essays that aren’t about you: I know this sounds obvious. I like the advice I heard an HBS alum give recently: After you’ve written your essay, ask yourself, “Could this essay also describe someone else?” If so, it probably isn’t personal enough to add to your overall application, and you likely need to do some more introspection. For example, we occasionally receive essays that talk at great length about HBS or an element of the program like the case method, but only share a tiny bit about the person themselves. That’s a missed opportunity to bring us into your world, your decisions, your motivations or your formative experiences.


Who should I ask to write my letters of recommendation?
Ask people who know you well in a work context. In most cases, one of the two should be your direct supervisor. The other can be someone you’ve worked with in the past or you are working with in a different capacity now. Depending on where you’re working, you can also consider a client, an investor or someone from a partner organization. Recs from professors are typically not as helpful in our process unless you’ve worked with them in a significant way.
It is a good idea to think about how the two recommendations can complement one another by drawing on different examples or aspects of your background. 
What if I am not telling my employer that I am applying to business school?
We understand, and we do not want your situation at work (promotions, bonus, etc.) to be negatively affected. If you’re in this situation you can ask someone from a prior job, or someone that you work with outside of your organization to write for you. 
Does it matter if my recommender is an alumna/alumnus of HBS? How important is her/his title?
You should always choose people who know you well over someone who may be an HBS alum or have a big title. Remember, we are trying to get to know YOU, not your recommender. 
What guidance (if any) should I give my recommender?
It is fine to share with your recommenders drafts of your application and essay and discuss with them areas where you think their perspective can help round out your story. It is NOT ok to draft letters of recommendation or any portion of them for your recommender.
Can I send in additional letters of recommendation or support?
No. And please don’t encourage people to write in on your behalf. It is not helpful. We review two letters of recommendation for each applicant.
What makes for a great recommendation? 
Rather than general platitudes, the best recommendations provide specific examples. That helps us understand the impact you have had and how you get things done. How are the people and the places in your world better because you were there? And, just as important, recommenders should be forthright about the feedback they’ve shared—we are all working on getting better at something and your recommenders’ perspectives on your growth help us understand your journey and your potential.